/*
Error: Invalid CSS after ".position-zero": expected selector, was "($position:0px)"
        on line 7 of margin.scss

2: //  margin-top: @margin-top;
3: //  margin-right: @margin-right;
4: //  margin-down: @margin-down;
5: //  margin-left: @margin-left;
6: //}
7: .position-zero($position:0px){
8:     top: $position;
9:     right: $position;
10:     bottom: $position;
11:     left: $position;
12: }

Backtrace:
margin.scss:7
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/scss/parser.rb:1278:in `expected'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/scss/parser.rb:1208:in `expected'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/scss/static_parser.rb:21:in `parse_selector'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:438:in `visit_rule'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/base.rb:36:in `visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:162:in `block in visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/stack.rb:79:in `block in with_base'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/stack.rb:135:in `with_frame'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/stack.rb:79:in `with_base'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:162:in `visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/base.rb:52:in `block in visit_children'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/base.rb:52:in `map'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/base.rb:52:in `visit_children'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:171:in `block in visit_children'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:183:in `with_environment'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:170:in `visit_children'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/base.rb:36:in `block in visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:190:in `visit_root'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/base.rb:36:in `visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:161:in `visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/visitors/perform.rb:10:in `visit'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/root_node.rb:36:in `css_tree'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/tree/root_node.rb:29:in `render_with_sourcemap'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/engine.rb:389:in `_render_with_sourcemap'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/engine.rb:307:in `render_with_sourcemap'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/plugin/compiler.rb:462:in `update_stylesheet'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/plugin/compiler.rb:215:in `block in update_stylesheets'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/plugin/compiler.rb:209:in `each'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/plugin/compiler.rb:209:in `update_stylesheets'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/plugin.rb:82:in `update_stylesheets'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/exec/sass_scss.rb:340:in `watch_or_update'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/exec/sass_scss.rb:51:in `process_result'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/exec/base.rb:52:in `parse'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/lib/sass/exec/base.rb:19:in `parse!'
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/sass-3.5.4/bin/scss:13:in `<top (required)>'
C:/Ruby22-x64/bin/scss:23:in `load'
C:/Ruby22-x64/bin/scss:23:in `<main>'
*/
body:before {
  white-space: pre;
  font-family: monospace;
  content: "Error: Invalid CSS after \".position-zero\": expected selector, was \"($position:0px)\"\A         on line 7 of margin.scss\A \A 2: //  margin-top: @margin-top;\A 3: //  margin-right: @margin-right;\A 4: //  margin-down: @margin-down;\A 5: //  margin-left: @margin-left;\A 6: //}\A 7: .position-zero($position:0px){\A 8:     top: $position;\A 9:     right: $position;\A 10:     bottom: $position;\A 11:     left: $position;\A 12: }"; }
